Change the default value of programs.ssh.forwardX11 to false.

Forwarding X11 to untrusted servers is extremely insecure; see for example
http://www.hackinglinuxexposed.com/articles/20040705.html
Merge master.
Fixed the documentation for programs.ssh.forwardX11 to account for the X11 SECURITY extension.
Merge pull request #40 from falsifian/master

Change the default value of programs.ssh.forwardX11 to false.
Add option for specifying shell aliases, environment.shellAliases.
Add nslcd (nss-pam-ldapd) uid and gid
Add support for nslcd (nss-pam-ldapd) as users.ldap.daemon option
Merge pull request #33 from rickynils/nslcd

Adds the option users.ldap.daemon which, handles NSS and PAM requests by talking to a local nslcd daemon instead of directly to the LDAP server.
Merge pull request #29 from rickynils/shellaliases

Generate shell aliases programatically
Add ec2.metadata (default false) option whether to allow access to EC2 metadata API.
sane: update name of the snapshot version of the backends
Changing the kernel parameters for crashump

I think that these enable more checks, and make more NMIs happen.
system-tarball-pc: fixing the readme inclusion
Renamed tcpWrapper -> tcp_wrappers
Get rid of the last uses of mkAlways

mkAlways is an insane function, mkMerge is much saner.
dhcpcd: disable "require dhcp_server_identifier" because of so many non-compliant DHCP servers
scanner support: create scanner group. Users need to be in this group to access scanners.
Installer test: fix nix-push call

http://hydra.nixos.org/build/3331147
Add options for specifying binary caches

Cherry-picked a4bcb26b1a3894022b08381079c2c402d49d611f.
Use the binary cache in the installer

Also remove "nixos-rebuild pull".